Tunable Mobile Excitons in 2D Materials

Transport of optical excitations in semiconducting solids plays a central role from both fundamental and technological perspectives. In systems with strong Coulomb interaction the propagation of optically injected carriers is dominated by excitons instead of free electrons and holes. In this context, two-dimensional van der Waals materials offer a broad range of strategies to tune excitonic movement employing a variety of approaches, including application of external fields, electrical charge injection, as well as dielectric and strain engineering. Here, I will discuss manipulation of mobile excitons using electrical gating and external strain fields. The focus will be placed on creating quasi-one-dimensional transport channels using combinations of monolayer materials and nanowires, as well as the impact of free charge carriers on the exciton propagation. I will present evidence for externally engineered anisotropic diffusion as well as non-trivial dependence of exciton mobility on free carrier density.